摘要： Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 5, 阅读全文

摘要： Description: Count the number of prime numbers less than a non-negative number, n. 本题不知道为什么，不可以使用hashtable来做，如果用了就超时了，只能用数组来存储，代码如下： 阅读全文

摘要： Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For exa 阅读全文